A team of U.S. researchers says it has found the first evidence of bacteria living in a cold, dark, fresh-water lake deep under the ice sheet in west Antarctica. The find could provide important insights into a vast ecosystem of microscopic life believed to be thriving in sub-glacial Antarctic lakes. It could also yield new clues to how life might survive in extreme environments on other planets and moons throughout the universe.

The U.S. team spent weeks drilling through about 1000 meters of ice to reach the 60-square kilometer, 2 meter-deep Lake Whillans. It's one of hundreds of freshwater lakes sandwiched between Antarctica's land surface and the massive ice sheet that covers it.

The samples retrieved from Lake Whillans, using a drilling system designed to prevent microbial contamination of the lake, showed cell structures and chemical evidence of DNA. But the scientists say more tests will be needed to confirm these results, once they have returned to the United States.

The water in some of these lakes has been isolated from the rest of the planet for millions of years, and scientists have been excited by the opportunity to study the water and lake-bottom sediment for signs of life.

Lake Whillans is different than many other sub-glacial lakes in that scientists believe its waters have been regularly mingling with meltwater from the overlying ice. But the U.S. researchers hopes the Lake Whillans bacteria can shed light on how so-called extremophile organisms survive without light or air, and how such microbes might also be altering the chemistry of the ice itself.

Two other drilling teams, one from Britain and the other from Russia, have also been drilling down to lakes at other locations on the icy Antarctic continent. The British team was unsuccessful in its quest to penetrate Lake Ellsworth, but one year ago Russian scientists successfully drilled through 3 kilometers of ice to reach Lake Vostok, thousands of kilometers away on the Eastern Antarctic Ice Sheet. Samples the Russians took earlier this year from the ancient frozen lake have yet to be analyzed.

The U.S. scientific project, called WISSARD, for Whillans Ice Stream Subglacial Access Research Drilling, is supported by $10 million from the National Science Foundation and other grants.